Vaccinating cattle against E. coli could cut human cases by 85%

Published on: Sep 16, 2013

Vaccinating cattle against Escherichia coli O157 could cut the number of cases of the disease in people by 85%, according to scientists with Scotland's University of Glasgow and others.

The bacteria, which can cause severe gastrointestinal illness in humans, can be spread by consuming contaminated food and water or by contact with livestock feces in the environment.

The vaccines that are available for cattle are rarely used, but the latest study suggests the public health benefits could be significant, an announcement from the university said.

The research was led by a team of researchers at the University of Glasgow in collaboration with the University of Edinburgh, the Royal Veterinary College, Scotland's Rural College, Health Protection Scotland and the Scottish E. coli O157/VTEC Reference Laboratory.

The study, published in the online journal PNAS, used veterinary, human and molecular data to examine the risks of E. coli O157 transmission from cattle to people, and to estimate the impact of vaccinating cattle.

The risk of E. coli O157 infection is particularly significant when the cattle are 'super-shedding' — excreting extremely high numbers of bacteria in their feces for a limited period of time. Vaccines against the bacteria exist that can reduce super-shedding, the researchers said.

As a consequence, the researchers predict that vaccinating cattle could reduce human cases by nearly 85%, far higher than the 50% predicted by studies simply looking at the efficacy of current vaccines in cattle.

These figures provide strong support for the adoption of vaccines by the livestock industry, and work is now underway to establish the economic basis for such a program of vaccination. In addition, research is continuing in Scotland by the same collaborative grouping to develop even more effective vaccines that would further reduce the impact on human disease.

Lead author Dr. Louise Matthews, senior research fellow in the Institute of Biodiversity, Animal Health & Comparative Medicine, said, "E. coli O157 is a serious gastrointestinal illness. The economic impact is also serious — for instance studies in the U.S. suggest that healthcare, lost productivity and food product recalls due to E. coli O157 can cost hundreds of millions of dollars each year.

"Treating cattle in order to reduce the number of human cases certainly makes sense from a human health perspective and, while more work is needed to calculate the cost of a vaccination program, the public health justification must be taken seriously," Matthew added.

The vaccines that are available currently have poor take-up: one version in the U.S. is not fully licensed because medicines for veterinary use must show that animal health is improved. This is problematic because E. coli O157 does not harm cattle and assessing the impact of treatment involves coordination between human and veterinary health practitioners.